Synch

Hi,

The following plots show the paths of the gator as obtained by particle tracking using the video (blue), radar (red) and the garmin GPS we used on the gator.

Radar is quite noisy because the "beach" was very narrow, so it may happen that sometimes the PT algorithm picked a breaking wave or it got confused with the dune. I used the GPS points as predictor-corrector data, in the sense that if a tracked point position was more than 15 m. away from the closest GPS point, it will reset the position of the track to the GPS position for the next iteration. GPS points are thus not included in either the video or radar tracks.

The following plots correspond to the 5 runs where we have all the data. The left panel is time (seconds since midnight) against FRF x coordinate, and the right panel is time against FRF y.

Gaps in the video record typically correspond to areas where data was missing. Most noticeable is that Camera 0 died, but I am expecting to use the full frame to fill this gap. However, it seems that most of the data in that camera will be straight lines, with little structure to quantify the lag.

Gaps in the radar record are areas where a clear identification of the target was not possible.

It must be noted that the video is subject to misregistration, since the pixels were defined at z=0, but the gator traveled at higher elevations. Since we can not correct for this, more important than the actual positions are the relative motions.

Radar 2211031-Video 1186669740- Aug 09, 2007- 14:30 GMT (1030 EST)



Not too much structure in this one. We basically made alongshore transects, and we turned south of the pier. It didn't help that the radar started 1 minute or so later.

Radar 2211100-Video 1186671480- Aug 09, 2007- 15:00 GMT (1100 EST)



One of the best for our purposes. We did doughnuts near the pier, which can be seen as the periodic signal in bot x and y. The idle times near y=900 are affected by misregistration of the video. The second idle time can be used for synch as well as a "start" signal.

Radar 2211200-Video 1186675140- Aug 09, 2007- 16:00 GMT (1200 EST)



Pretty much useless. I can try to fine tune the radar track, but we made doughnuts near the radar antenna, where the dune grass affected significantly.

Radar 2211230-Video 1186677000- Aug 09, 2007- 16:30 GMT (1230 EST)



Another possibly good one. It has the added benefit that the radar gps was not reset, so it can give us a hint of the drift (if any).

Radar 2211400-Video 1186682340- Aug 09, 2007- 18:00 GMT (1400 EST)



Possibly good. Lots of radar noise, but clear y signal with doughnuts.

Now I am going to try to quantify the lag / drift/